Can't get WhatsApp to work on iPhone 16 Pro Max

I have an older phone - a samsung galaxy A 23 which is used at home with the house wifi but without a sim card. I have transferred the sim card to my Iphone 16. I then deleted the Whatsapp on my Samsung A 23 in order to download the whatsapp on to my Iphone 16max pro. The apple still sends the codes to the A23 which now does not have whatsapp. How am I going to retrieve this and apply it to my Iphone 16.

[Re-Titled by Moderator]